Reliable multicast file transfer on the inter-university satellite network

We developed a reliable multicast program module to transfer files efficiently on the inter-university satellite network which is called SCS (Space Collaboration System). SCS consists of 139 VSAT (very small aperture terminal) stations at universities and has been used for sharing classes, debates, and symposiums at distant places, exchanging audiovisual signals. To provide data sharing services, we try to install a function of the multicast file transfer to SCS as the first step of computer communications. Error control is necessary for the reliable file transfer. The program uses selective-repeat ARQ (automatic repeat request) with multiple transmissions. We implemented the reliable multicast file transfer program to two VSAT stations in order to measure the performance using a satellite link with a transmission rate of 1536 kbit/s and a terrestrial network of the 10 Mbit/s Ethernet. The results show a throughput of 1.3 Mbit/s including the overheads, which is the maximum performance of the multicast program in the network configuration.